After standardization of MPEG-2, new video compression standards (or audio compression standards) such as MPEG-4, H.264/AVC, scalable video coding (SVC), and the like, have been constantly developed over the past ten years. In addition, the respective new standards have expanded a utilization area of an MPEG standard while forming a new market. However, a transport technology such as an MPEG-2 transport system (TS) has continuously been widely used in digital broadcasting, mobile broadcasting (T-DMB, DVB-H, or the like), or the like, on the market for about twenty years and has been widely used even in multimedia transport through the Internet, that is, an IPTV service, that was not considered at the time of establishing an MPEG-2 standard.
However, a multimedia transport environment of the present time has been significantly changed from a transport environment at the time of developing the MPEG-2 TS, For example, the MPEG-2 TS standard has been developed in consideration of multimedia data transport through an ATM network at the time of establishment thereof; however, it is hard to find an example of using the MPEG-2 TS standard for this object at present. In addition, requirements such as multimedia transport using the Internet, or the like, at the time of establishing the MPEG-2 TS standard were not considered, such that elements that is not efficient for the recent multimedia transport through the Internet are present. Therefore, establishment of a MPEG multimedia transport layer (MMT), which is a multimedia transport standard considering a multimedia service in the Internet matched to a changing multimedia environment has been recognized as a very importance problem in the MPEG.
The reason why the MMT has been standardized as a new transport technology standard in the MPEG as described above is that since the MPEG2-TS standard established before twenty years are not optimized for a recent IPTV broadcasting service, Internet environment, or the like, the international multimedia transport standard optimized for a recent multimedia transport environment in various heterogeneous networks has been urgently demanded.
As described above, in the recent multimedia transport through the various heterogeneous networks, multiple transport units have been simultaneously used. With hybrid transport using the multiple transport units, various applications have been attempted.
Further, in the case in which a media content is transported in an IP environment, a single port stream is generally configured in a unit of four values, that is, a source IP address, a destination IP address, a source port number, and a destination port number of a sender and a receiver, and an application is formed in a port stream unit. In this case, how many ports are opened and used according to the application and which protocol (UDP or TCP) is selected are entirely an application implementation issue and may be freely selected, such that configurations of various transport scenarios are possible according to a degree of freedom of port mapping for each content component, selection of L3 protocol, or the like, due to characteristics thereof.